1. Field of the Invention
This invention relates generally to a surgical method for creation of an aortico-pulmonary shunt, and, more specifically, to a method which utilizes a catheter to create the shunt.
2. Background of the Invention
Congenital heart defects, which can cause obstruction of pulmonary blood flow and right-to-left shunting of blood result in a condition known as cyanosis, which manifests itself in infants in what is commonly known as the "blue baby" syndrome. The commonest such condition is the Tetralogy of Fallot, which appears is approximately two of each 10,000 live births, is one of the three most common forms of congenital heart disease necessitating what is typically surgical correction in the first year of life, and accounts for 10% of patients seen in larger pediatric cardiology clinics. Of those cyanotic patients over two years of age who have not yet required or received surgery, about 75% have the Tetralogy of Fallot. Additional background on the incidence of this condition is available in "Congenital Heart Disease in 56,109 Births--Incidence and National History," Mitchell et al , Circulation, Vol XLIII, March 1971, pp. 323-332, which is hereby fully incorporated by reference herein as though set forth in full
Conventional methods for treating this condition involve the surgical creation of a communication between the aortic and pulmonary circulations with the objective of increasing pulmonary blood flow, improved oxygenation, and relief of cyanosis. The first such procedure, known as the Blalock-Tarissig Shunt, involved creation of a shunt by anastomosing the proximal end of the divided subclavian artery to the left or right pulmonary artery.
These conventional methods all suffer from the disadvantage that they involve a major surgical procedure on a sick child. A second disadvantage is that all suffer from a lack of controllability of the size of the shunt, which is problematic, since a shunt which is too large may result in heart failure in the child, while a shunt which is too small will result in the child not achieving maximum benefit. A third disadvantage is the difficulty of increasing the size of the shunt as the child grows, and the difficulty of closing the shunt at the time of a surgical "total correction" of the congenital heart defect.
Accordingly, it is an object of the subject invention to provide a method of creating an aortico-pulmonary shunt which overcomes the disadvantages of prior art methods. Additional objects and advantages will be set forth in the description which follows or will be apparent to those of ordinary skill in the art who practice the invention.